a(0)=1, a(1)=5, a(n+2)=4a(n), n>0.

Terms

a(0) =1a(1) =5a(2) =8a(3) =20a(4) =32a(5) =80a(6) =128a(7) =320a(8) =512a(9) =1280a(10) =2048a(11) =5120a(12) =8192a(13) =20480a(14) =32768a(15) =81920a(16) =131072a(17) =327680a(18) =524288a(19) =1310720a(20) =2097152a(21) =5242880a(22) =8388608a(23) =20971520a(24) =33554432a(25) =83886080a(26) =134217728a(27) =335544320a(28) =536870912a(29) =1342177280